Internally expanding brake for vehicles



May 1o, 1949. 159mm 2,469,826

NTERNALLY EXPANDING BRAKE FOR VEHICLES Filed Aug. 24, 1944 2 Sheets-Sheet 1 May 10, 1949. L s, lRvlNG 2,469,826v

INTERNALLY EXPANDING BRAKE FOR VEHICLES Filed Aug. 24. 1944 2 sheets-sheet 2 Patented May 10, 1949 UNITED STATES PATENT OFFICE INTERNALLY EXPANDING BRAKE FOR VEHICLES .lohn Samuel Irving, Birmingham, England (Cl. 18S-78) In Great Brit 9 Claims.

This invention relates to improvements in brakes for vehicles and is particularly concerned with shoe separating or spreading means for brakes of the type in which a pair of opposed shoes mounted within-a brake drum are adapted to be urged outwardly into contact with the drum to apply the brake.

According to our invention adjacent ends of the shoe webs or abutment members mounted thereon are staggered and a bell-crank or equivalent lever is adapted to fulcrum on and rock about the end of one shoe Web or abutment member. One arm of the lever engages the other shoe web or abutment member while the other is acted on by a force applying means, as for example a cable or rod or a fluid pressure operated piston. Thus when a force is applied to the second arm of the bell-crank lever the force tends to rock the lever about its ulcrum and the fulcrurn and the rst arm urge the shoe ends outwardly in opposite directions into engagement with the brake drum.

A stop is provided for the shoe ends in the off position of the brake to facilitate the centering of the shoe assembly and this stop may be fixed to the back plate or may have a limited floating movement if desired.

To take the component of the force applied to the lever in a direction substantially at right angles to the line of movement of the shoe ends a roller may be mounted on or adjacent to the lever fulcrum, this roller rolling on the backplate or other fixed surface as the shoes move.

Some practical forms of shoe spreading means in accordance with our invention are illustrated by way of example in the accompanying drawings in which- Figure 1 is a section in a plane at right angles to the back plate of the brake of one form of shoe-spreading means and the adjacent parts of the shoes and back plate.

Figure 2 is a fragmentary section on a larger scale of the shoe-separating lever and the shoe ends showing the movement of the lever in the application of the brake.

Figure 3 is a plan of an alternative form of shoe-spreading means.

Figure 4 is a section through the mounting for the shoe-spreading means shown in Figure 3.

Figure 5 is an elevation of the shoe-spreading means shown in Figures 3 and 4 and the adjacent parts of the shoes.

Figure 6 is a section taken substantially on the line G-B of Figure 3 looking in the direction of 2 the arrows and omitting the ends of the brake shoes.

In Figures 1 and 2, 10, 11 are the webs of a pair of arcuate brake shoes mounted in the ordinary way on a stationary back-plate l2 and adapted to be expanded into contact with a rotating drum to apply the brake. The shoe webs il), Ii lie in the same plane parallel to the back-r plate, and there are riveted or otherwise secured to the adjacent ends of the webs flanged sheet metal pressings I3, lli which extend towards each other and the free ends of which are oppositely staggered to lie in spaced parallel planes. The extremity of the pressing I4 which lies nearest the back-plate is received in a longitudinal slot in a pivot-pin I5 of which the axis is parallel to the back-plate. This pin forms a fulcrum for a bell-crank lever I6, the lever having an arcuate notch Il at the junction of its limbs of substantially the same radius as the pin with which it engages. Rotatably mounted on the pin on each side of the lever is a roller I8 adapted to roll on the flat surface of a fitting I9 secured by studs 2B to the back-plate I2 in which a recessed opening is pressed to receive it. Notches are cut in the end of the pressing I4 to clear the rollers.

One arm of the bell crank lever I6 extends away from the back-plate and engages the free end of the pressing I3 on the shoe IB. The other arm extends towards the shoe I0 and normally lies at a small angle to the back-plate as shown in Figure 1. Pivotally connected to the iree end oi this arm is a fork end 2! to which is connected an actuating cable or rod 22 passing through an opening 23 in the tting I9 and having its axis at right angles to the back-plate.

A pull applied to the cable or rod 22 draws the second arm oi the lever i6 towards the back-plate as indicated by the dotted lines in Figure 2 and rocks the lever about its fulcrum, the pivot pin I5. The rst arm of the lever thus urges the shoe it outwardly towards the drum and at the same time the reaction on the fulcrum urges the shoe Il in the` opposite direction also into engagement with the drum. The leverage obtained depends on the respective lengths of the arms of the bell-crank lever and can be selected according to requirements. The component of the force applied to the lever which is directed towards the back-plate is taken by the rollers I8 which are free to roll on the fitting I9 so that there is no tendency for the shoes to be distorted or displaced laterally.

AV stop for the shoes in the off position is 32, 33 which extend towards eachother fromthe The projecting ends of the.

ends of the shoes. webs are offset in opposite directions from the central plane of the shoes and their lengths" are such that in the oi position .offthe'shoesi their extremities just overlap. Securedltonthe,

back-plate midway between the shoe ends isa steady post 34 having opposed notches 35,36 parallel to the back-plate to receive and form stopsy for `the vends `oftheshoes.` Thefwebs are located in a lateral direction by slitting ltheir ends which are wider than the postv 34 vand-cranking them as shown at 53T in Figure 3 `to 4engage theI outer `surface of thepost. The post 34"-is also-formed with a llongitudinal* s1ot'38intersecting the notches 35,365 This slot houses a iloatingy cranked' lever having 'one vlimbf`39 extending substantially at 'right vangles to the'back-plate andengaging the free end 'of thewebf 32 in the notch 35.' At the junction ofthe 'limbs -thelever is' notched to provide a surface ill which engages thefree-end of the-web 33 in the notch 36. The other limb '4 I -of- 'the lever extends substantially parallel tothe back-plate,A andv pivoted to `its free end is -a fork end- 42 'to which-'is `connected a tension rod-or cable E3. Adjacent the junction of the limbs the lever has a lug-44 which isy notched to receive the reduced central part of 'a roller 115 of bobbin form. The roller is--housed inv an enlargement of theelowerl end of the slot 38 in the-post and is yadapted'to roll on the lower surface-46 of theslot as shown moreparticula-rly Yin Figurer-5.

When-'a pullsis applied to the rod or cable 43 the lever fulcrums about its engagementwith the shoe web 33 and the limb 39 urges the web 321tofthe vleft in Figuresl k3 rand lifwhile--the reaction Yon the iulerum Vurges the yweb 33 to the right. The component of theforcevappliedfto the levery acting'inthe direction of'the'backplate is 4taken by the roller 45 rolling on the surface 4B.'

In the arrangement shown in Figures 1 and-2 the roller is co-axial or substantially so with the point about which the lever rocks,butinthe'ar rangement slfiown'inFigures 3 vto G'the roller is spaced from the'fulcrum; and nto allow for the angularmovement ofthe leverV about its fulcrum when the brake is vapplied the `surface-'16 with which theroller engages 'may' be curved.'`

ToA` allow lfor theangular movementof-the shoesabouttheir pivots in theJ application of the brake or adjustment of the shoes the lever instead of being arranged to rock-about a pinV in the shoev end as shownin Figures 1 and'Z maybe so mounted that it can rock in two planes at right-'angles to each other relative to the shoes.r`

I claim:

1. Shoe separating means `for a brakeiofthe type set forth comprising,A opposedVK staggered abutments in adjacent shoe ends, a post xedto the back-plate of the brake and having `opposed notches to receive the abutments for vwhich'it forms a stop in the off positionyof the shoes, va crankedftwo-armed lever fulc'ruming' on one of said abutments, one arm of said lever extending substantially at right angles to the back-plate and engaging the other abutment, the second arm of the lever extending substantially parallel to the back-plate, and means for applying to the second arm a force directed substantially at right angles to the back-plate to rock the lever about its fulcrum.,

2.` Shoe separating means as claimed in claim Lin which the lever is housed in a longitudinal slot in the post intersected by the notches in which4 the staggered abutments are received.

3. Shoe separating means for a brake of the typeset forth having a pair of movable brake shoes comprising'opposed abutments on adjacent shoe'endsysaid abutments being offset on opposite sides ofthe median plane of the shoes and substantially opposite each other, a full-floating cranked two-armed lever in free rocking engagement with both of' said abutments, one arm of said- -lever extending between `said abutments andr'the second-arm= extending inA `a direction substantiallyparallel to the ba-clr-plate of' the brake andfgenerallygin the median-plane of the shoes, the engagement 'of said two-armed Alever withl said abutments serving to maintain said lever in operating position, andmeans for applyingA aforce to vthe second. arm to 'move the lever angularly.

4*.- Shoefseparatingmeans for a' brake of the type setfforth-havingja pair Vo-movable brake shoes comprisingiopposed abutments on adjacent shoe ends, saidabutments being offset on opposite-sides of'the median plane *of* the shoes andsubstanti'ally opposite each other, a iullfloatingcranked two-armed lever in freefrocking engagementwithL bothof said abutments',l one arm A'of 'the'lever' 'extending in a-,direction sub-` stantially- "at 'right angles tto the back-plate .of the brake betweensai'd abutmentsa pivot-pin mounted on one of `said abutments with its axis parallel to the back-plate of thebrake, one face of-said pin being engaged bythe lever, the engagement of'sai'd two-armedlever with one of said vabutments and with Asaid pivot pin serving to 'maintain said-v leverin` operating position, a roller mounted on said'pinrand` rolling'on the 'bach-plate,a-secondA arm .of the lever extending substantially; parallel to` the back-plate and generally in=A the v'median' plane ofA `the shoes,. and means for -applying a force'to the second arm of. the lever to move-the 4lever angularly:

5J Shoe/separating means for abrake'orthe type set'l forth. comprising opposed staggered abutments on adjacent shoe vends, a post iixed to the `bachi-plate 'ofthe vbrake and1 having opposed notches to receive the abutments for which' it formsl a stop in the-"ofP position of the shoes, a longitudinalL slot ykirl 'the post in-tersectedl bysaid notches', a1crankedztwo-armed lever oli-which one arm is housed in said sloth'andextendsbetweenl the-abutments :with iwhich it Eis in free rocking engagement andfthe :other armextends Asubstantiallymaral'lekto the-'back-pl'ate andmeans for applying to said latter armrafforce directedfsube stantially at.v vright angles to.; the4 back-plate to move the lever angularly.

6. -Shoeseparating: means/:as claimed inlzclaim jacent .the junction :of zthe armssaid roller beingadaptedto rollon a surface: at theend ofv .the

type set" forth' having... apair `of,mevable brake;y

shces,comprising opposed abutments on adjacent shoe ends, said abutments being offset on opposite sides of the median plane of the shoes and substantially opposite each other, a fullfloating cranked two-armed lever in free rocking engagement with both of said abutments, one arm of said lever extending substantially at right angles to the back-plate of the brake between said abutments and the other arm extending substantially parallel to the back-plate and generally in the median plane of the shoes, the engagement of said two-armed lever With said abutments serving to maintain said lever in operating position, and means for applying a force to the latter arm to rock the lever angularly.

8. Shoe separating means for a brake of the type set forth having a pair of movable brake shoes, comprising opposed abutments on adjacent shoe ends, said abutments being offset on opposite sides of the median plane of the shoes and substantially opposite each other, a fulliloating cranked two-armed lever in free rocking engagement With both of said abutments, one arm of said lever extending substantially at right angles to the back-plate of the brake between said abutments and the other arm extending substantially parallel to the back-plate and generally in the median plane of the shoes, the engagement of said two-armed lever with said abutments serving to maintain said lever in operating position, means for applying a force to the latter arm to rock the lever angularly, and means for taking the component of the force applied to the lever in a direction substantially at right angles to the back-plate.

9. Shoe separating means for brakes of the type set forth having a pair of movable brake shoes, comprising opposed abutments on adjacent shoe ends, said abutments being offset on opposite sides of the median plane of the shoes and substantially opposite each other, a fulloating cranked two-armed lever in full rocking engagement With both of said abutments, one arm of said lever extending substantially at right angles to the back-plate of the brake between said abutments, a roller mounted on said lever adjacent the junction of the arms and adapted to roll on the back-plate of the brake, a second arm of the lever extending substantially parallel to the back-plate and generally in the median plane of the shoes, the engagement of said twoarmed lever With said abutments serving to maintain said lever in operating position, and means for applying a force to said second arm to rock the lever angularly.

JOHN SAMUEL IRVING.

REFERENCES CITED The iol-lowing references are of record in the le of this patent:

UNITED STATES PATENTS Number Name y, Date 2,006,494 Bendix et al July 2, 1935 2,173,615 Sheldrick Sept. 19, 1939 2,192,001 Bolster Feb. 27, 1940 2,395,551 Irving et al Feb. 26, 1946 

